Cups? Check. Timer? Check. Major endorsements? Check. Welcome to the world of sport stacking

Steven Purugganan, 11, broke the world record and got an endorsement deal from McDonald's.

Blink and you might just miss it. The blur of crisscrossing hands and zigzagging neon cups is probably the weirdest organized sport you've never heard of. Dubbed sport stacking, this rapid-fire competition could at first glance be mistaken for some peculiar carnival game. Players are tasked with arranging 12 lightweight plastic cups into various formations; a stacking kit comes with a touch-pad timer and cups that have a trio of holes in the bottom to reduce air resistance. At slower speeds, it seems easy enough: build up pyramids and break them down in a predetermined sequence. But as the game has...